There has been proposed a technical method to have a navigation-client reproduce a route searched by a navigation server according to a communication between the navigation server and the navigation-client mounted in a vehicle or the like (refer to Patent Document 1).
In particular, link identification information for identifying a link constituting a part of a server route searched by the navigation server is transmitted to the navigation-client. According to this, information of coordinate rows of latitude and longitude expressing the link associated with the link identification information is read out from a storage unit, and a client route is searched and output based on the coordinate row information by the navigation-client. On such occasion, a client route which completely or almost completely matches the server route can be searched by performing interpolation processing for connecting discontinuous portions which cannot be supplemented only by the link identification information sent from the navigation server.